CN113908870A

CN113908870A - Controllable preparation of bifunctional non-noble metal nitride catalyst and application of bifunctional non-noble metal nitride catalyst in high-current urea electrolysis hydrogen production

Info

Publication number: CN113908870A
Application number: CN202010578768.2A
Authority: CN
Inventors: 蔡凤明; 廖礼玲; 蒲景阳; 周海青; 余芳
Original assignee: Hunan Normal University
Current assignee: Hunan Normal University
Priority date: 2020-06-23
Filing date: 2020-06-23
Publication date: 2022-01-11
Anticipated expiration: 2040-06-23
Also published as: CN113908870B

Abstract

The invention discloses a controllable preparation based on an inexpensive bifunctional non-precious metal nitride nano-porous heterojunction and research on high-current electrolysis of urea for hydrogen production, belonging to the fields of electrocatalytic material hydrogen production and fuel cell research. The main points of the technical solution of the present invention: using the mixed solution of Fe(NO ₃ ) ₃ .9H ₂ O and ethanol as the precursor, the commercial foam metal substrate (foamed nickel, cobalt, cobalt nickel or iron, etc.) is surface-modified, and then subjected to high temperature NixFeN/Ni ₃ N (x=1, 3) nano-heterojunction catalysts were obtained by nitridation treatment. This unique heterojunction catalyst benefits from the metallicity of metal nitrides, the ^three -dimensional nanoporous structure, and the strong chemical bonding between different nitrides. The overpotentials for catalytic oxygen evolution and urea oxidation are only 293 and 162 mV. The electrocatalyst material has broad application prospects in the green preparation of hydrogen energy and fuel cells, can achieve high-efficiency, high-current stable hydrogen production and urea pollution treatment, and promote the development of the hydrogen energy industry.

Description

Controllable preparation of bifunctional non-noble metal nitride catalyst and application of bifunctional non-noble metal nitride catalyst in high-current urea electrolysis hydrogen production

Technical Field

The invention discloses an electrocatalytic material used in the research field of hydrogen production by water electrolysis and fuel cells, and particularly relates to controllable preparation of a bifunctional non-noble metal nitride nano porous catalyst and research on hydrogen production by high-current urea electrolysis, so as to realize efficient hydrogen production reaction by water electrolysis under high current, greatly reduce energy consumption in the alkaline water electrolysis process, and realize high-current efficient hydrogen production.

Background

The energy is an important material basis for human survival and development, and has a decisive role in clothes and food residence, social and economic development and the like. However, excessive consumption of fossil fuels and the accompanying environmental pollution problem compel people to search and develop renewable clean energy sources with abundant reserves. The hydrogen energy is used as a clean, sustainable, high-calorific-value and high-energy-density energy carrier, is easy to store and convert, has rich content in the universe, has no pollution and zero emission, is considered as an ideal energy for replacing fossil fuels in the future, and is expected to play a vital role in the future energy structure layout of China. Therefore, realizing the macro-production of hydrogen is an important prerequisite to promote the application of hydrogen energy. Among a plurality of hydrogen production processes, the water electrolysis hydrogen production technology can be used for preparing hydrogen by water decomposition driven by renewable energy sources such as wind, water, light and the like, and the three-abandon problem of wind abandonment, water abandonment, light abandonment and the like is relieved, so that the water electrolysis hydrogen production technology is paid attention to by broad students. However, as one of the half-reaction anode Oxygen Evolution Reactions (OERs) of electrolyzed water, the complex four-electron transfer process thereof leads to slow reaction kinetics, requires a considerable overpotential matching hydrogen production rate, becomes a bottleneck of the overall efficiency of the electrolyzed water reaction, and greatly limits the hydrogen production efficiency and the energy conversion efficiency. The method prompts a non-noble metal oxygen evolution catalyst with low cost, high activity and high stability to replace commercial catalysts with high price such as Ru, Ir and the like to promote an OER reaction, or selects a new anode reaction with low overpotential to match with a cathode hydrogen evolution reaction, so as to realize the high-efficiency hydrogen production reaction by electrolyzing water. The urea has the advantages of wide source, no pollution, low operation voltage (0.37V) of a catalytic theory and the like, so that the urea fuel becomes an ideal substitute of a hydrogen fuel and water cracking system, the function of pollutant treatment can be realized, efficient hydrogen production can be realized, and the energy consumption in the water cracking process is reduced. However, urea oxidation performance is limited by 6 electron transfer, and many urea oxidation catalysts are very unstable in alkaline environments and can only operate stably for less than 1 hour. In consideration of potential industrial application, a need exists for developing a bifunctional non-noble metal catalyst which has excellent electrocatalytic oxygen evolution and Urea Oxidation (UOR) performances and is stable at high current, so that a suitable anode reaction is selected to match a cathode hydrogen evolution reaction according to needs, and the high-performance electrocatalytic oxygen evolution and urea oxidation catalyst has wide application in solving the aspects of environmental pollution, greenhouse effect, energy shortage and the like. Unfortunately, no such bifunctional non-noble metal catalysts have been reported, and most of them exhibit excellent urea oxidation performance, but are very unstable. Therefore, the development of an efficient and cheap anode material and other high-performance hydrogen evolution catalysts together to construct an asymmetric two-electrode water splitting device is needed to promote efficient hydrogen production. Therefore, in the patent, a high-performance double non-noble metal nitride nano porous hierarchical structure is designed on commercial nickel foam, and high-efficiency oxygen evolution and urea oxidation catalytic performance is realized at the same time, so that the electric energy consumption of electrolytic water reaction is reduced, the aim of realizing stable hydrogen production with large current and reducing urea pollution is fulfilled, and the development of the hydrogen energy industry is promoted.

Disclosure of Invention

The invention aims to provide a bifunctional non-noble metal nitride nano porous catalyst applied to the hydrogen production by electrolyzing urea with large current. Alkaline metal nitride heterojunction catalyst obtained by room temperature corrosion and chemical vapor deposition methodExcellent OER and UOR reaction activity is shown in the environment. For example, Ni_XFeN /Ni₃The N (x =1, 3) heterojunction only needs 293 and 162 mV overpotential to drive large current density 500 mA/cm²Oxygen evolution and urea oxidation catalytic performance, and excellent stability at large current, but few reports are made to the bifunctional catalyst which can efficiently evolve oxygen and urea oxidation and has stable large current internationally, wherein the overpotential of UOR is reduced by about 130 mV relative to OER reaction, which is important for improving the energy efficiency of water electrolysis hydrogen production reaction.

The preparation method of the non-noble metal catalyst comprises the following steps:

step 1: the foam substrate was cut to an area of 12 mm length by 6 mm width.

Step 2: cleaning the foam metal substrate, wherein the cleaning and cleaning steps are as follows: and (3) soaking the foam substrate of the substrate material in 3M hydrochloric acid, absolute ethyl alcohol and deionized water respectively, and ultrasonically washing for 10 minutes to finish washing.

And step 3: the method for preparing the nickel-iron oxide precursor comprises the following steps: 0.5 g of Fe (NO)₃)₃· 9H₂And (3) fully dissolving O in 5 mL of alcohol solution to serve as a precursor solution for modifying the foam substrate in the step (2), and then naturally airing in the air. And 4, step 4: putting the nickel-iron oxide precursor obtained in the step 3 in the center of a tubular furnace temperature zone for thermal nitrogen treatment, setting the central temperature of the tubular furnace to be 400 ℃ for 2 h with the constant temperature of 3 ℃/min by taking 100 sccm ammonia gas as a nitrogen source and inert gas argon as protective gas, and obtaining primary Ni nitride₃FeN/Ni₃An N heterojunction catalyst.

And 5: mixing Ni in step 4₃FeN/Ni₃Soaking the N heterojunction catalyst in the precursor solution obtained in the step (3) for 2-3s, airing at room temperature, and repeating the step (4) to obtain the final Ni_XFeN /Ni₃N (x =1, 3) nano-heterojunction catalyst.

Compared with the existing electrocatalyst material, the invention has the following different characteristics:

1. the invention synthesizes the bifunctional non-noble metal nitride nano porous heterojunction catalyst based on the foam metal substrate, the preparation process is simple, the operation condition is mild, and the nitridation process is easy to control and repeat.

2. Electrocatalyst material Ni of the invention_XFeN /Ni₃The N (x =1, 3) nano heterojunction catalyst has the advantages that the metal nitride with high specific surface area is prepared by adopting a chemical vapor deposition method, has special electronic structure and metalloid property, has excellent capability in the aspect of electronic conduction, and benefits from the three-dimensional mesoporous structure, NiFeN and Ni of the nano catalyst material₃Strong chemical bonding between N and high conductivity of the catalyst itself, Ni_XFeN /Ni₃N (x =1, 3) exhibits excellent OER and UOR catalytic activity. In alkaline environment, only 293 and 162 mV bottom overpotential is needed to drive 500 mA/cm²Current density, and commercial IrO₂In contrast, the catalyst exhibits excellent catalytic activity.

3. Electrocatalyst material Ni of the invention_XFeN /Ni₃The advantage of N (x =1, 3) nano-heterojunction catalyst is that, in addition to efficient oxygen evolution and urea oxidation, it is important to be able to maintain excellent stability and very strong corrosion resistance at high currents, which is reported very little internationally.

Description of the drawings fig. 1 shows the electrocatalyst material Ni in the first and after 1000 cycles in example 1 of the invention_XFeN /Ni₃Current-potential polarization plot of N (x =1, 3) in alkaline 1M KOH solution. FIG. 2 is a graph showing the stability of the electrocatalytic oxygen evolution reaction of the electrocatalyst material according to example 1 of the invention. FIG. 3 shows the electrocatalyst material Ni during the first and after 1000 cycles in example 2 of the present invention_XFeN /Ni₃Current-potential polarization plot of CV of N (x =1, 3) in 1M KOH + 0.5M urea solution. FIG. 4 shows the catalyst material of example 2 of the present invention at a high current of 1000 mA/cm²The stability test of the electrocatalytic urea oxidation reaction was performed. FIG. 5 is an SEM image of the catalyst material of examples 1 and 2 of the present invention before reaction. Figure 6 is an XRD pattern before reaction of the catalyst material in examples 1, 2 of the present invention. FIG. 7 shows the results of example 3 of the present inventionAnd (3) comparing the catalytic activities of the oxygen evolution catalysts synthesized by the ferric nitrate solution precursors with different concentrations. Fig. 8 is a comparison of catalytic activities of metal nitride catalysts synthesized from ferric nitrate solution precursors of different concentrations according to example 3 of the present invention in urea oxidation reactions.

Detailed description of the inventionwhile the foregoing will provide a better understanding of the nature of the patent, it is to be understood that the invention is not limited in its application to the details of the examples set forth below, since the above-described techniques may be practiced without departing from the spirit of the invention. An example of the application of the bifunctional non-noble metal nitride nano-porous catalyst in the high-current electrolytic water oxygen evolution and urea oxidation reaction is as follows. Example 1 Ni_XFeN /Ni₃Preparation of N (x =1, 3) nano heterojunction catalyst and application of the N (x =1, 3) nano heterojunction catalyst in electrocatalytic oxygen evolution reaction in 1M KOH environment. Step 1: the method for preparing the nickel-iron oxide precursor comprises the following steps: 0.5 g of Fe (NO)₃)₃ · 9H₂And O is fully dissolved in 5 mL of alcohol solution to be used as precursor solution for modifying a clean foam metal substrate, and then the foam metal substrate is placed in the air for naturally drying. Step 2: placing the modified foam substrate in the center of a tubular furnace temperature area for nitriding treatment, taking inert gas argon as protective gas, taking 100 sccm ammonia gas as a nitrogen source, setting the temperature of the center of the tubular furnace to be 400 ℃, keeping the temperature for 2 hours, and setting the heating rate to be 3 ℃/min to obtain the primarily nitrided Ni₃FeN/Ni₃N nano heterojunction catalyst. And step 3: continuing to soak the nitride sample in the step 2 in the ferric nitrate solution for 2-3s, airing at room temperature, and repeating the step 2 to obtain the final Ni_XFeN /Ni₃N (x =1, 3) nano-heterojunction catalyst. The electrocatalytic oxygen evolution performance is mainly tested by using a standard three-electrode system (working electrode, counter electrode and reference electrode) by using an American well-known brand GARY Reference 30000 or 600+ electrochemical workstation. Wherein Ni_XFeN /Ni₃The results of electrochemical tests using N (x =1, 3) nano-heterojunction catalyst as the working electrode, Hg/HgO electrode as the reference electrode, platinum wire as the counter electrode, and 1M KOH solution as the electrolyte solution are shown in fig. 1, fig. 2, and fig. 1As shown in fig. 7. Example 2 Ni_XFeN /Ni₃Preparation of N (x =1, 3) nano-heterojunction catalyst and electrocatalytic urea oxidation performance test in 1M KOH + 0.5M urea environment. The preparation of the nano-heterojunction catalyst was the same as in example 1. Electrochemical Urea Oxidation Performance was tested using a standard three-electrode system, mainly using the United states brand GARY Reference 3000 or 600+ electrochemical workstation, where Ni_XFeN /Ni₃The N (x =1, 3) nano heterojunction catalyst is used as a working electrode, the Hg/HgO electrode is used as a reference electrode, the platinum wire is used as a counter electrode, and the electrolyte is mainly 1M KOH + 0.5M urea solution. The results of the urea oxidation tests are shown in fig. 3, 4 and 8, the surface morphology of the corresponding nano-heterojunction catalyst is shown in fig. 5, and the X-ray diffraction pattern characterizing the crystal structure and composition is shown in fig. 6. Example 3 Ni_XFeN /Ni₃Preparation of N (x =1, 3) nano heterojunction catalyst under different ferric nitrate concentrations and application thereof in electrocatalytic oxygen evolution and urea oxidation reaction. Step 1: the ferronickel oxide precursor is prepared by the following method, 0.75 g, 0.5 g and 0.4 g Fe (NO) respectively₃)₃ · 9H₂And O is fully dissolved in 5 mL of ethanol to prepare different concentrations of the sediment solutions, a clean foam nickel substrate is modified, and then the foam nickel substrate is naturally dried in the air. The material growth procedure of example 1 was repeated to obtain Ni_XFeN /Ni₃N (x =1, 3) nano-heterojunction catalyst. The test equipment for the electro-catalytic oxygen evolution performance adopts an American brand GARY Reference 3000 or 600+ electrochemical workstation and adopts a standard three-electrode device for testing. Wherein Ni_XFeN /Ni₃The N (x =1, 3) nano heterojunction catalyst is used as a working electrode, the imported Hg/HgO electrode is used as a reference electrode, the platinum wire is used as a counter electrode, and the corresponding catalytic oxygen evolution and urea oxidation performances are respectively tested in 1M KOH and 1M KOH + 0.5M urea electrolyte, and the test results are shown in fig. 7 and 8. While the above examples illustrate the basic preparation process of the present invention and the broad application of the catalyst (electrolysis of water to produce hydrogen), those skilled in the art will appreciate that the present invention is not limited to the above examples, which are presented in the specification to illustrate the principles of the present invention and to show the sameThe preparation process of the invention can be changed and modified within the scope of the principle of the invention, and the changes and modifications fall into the protection scope of the invention.

Claims

1. This patent takes the double non-precious metal nitride nanoporous hierarchical structure catalyst as an example to illustrate the preparation of cheap and efficient electrocatalytic materials and the research on their bifunctional electrocatalytic properties (oxygen evolution from water electrolysis and urea oxidation). The preparation method of the bifunctional non-precious metal nitride catalyst studied in the current electrolysis of urea for hydrogen production is as follows: Step 1: First, an appropriate proportion of Fe(NO ₃ ) ₃ · 9H ₂ O was dissolved in 5 mL of alcohol as a precursor solution, and the To modify the nickel foam substrate ultrasonically cleaned with concentrated hydrochloric acid, alcohol and deionized water in advance, and then place the sample in the air to dry naturally, the nickel-iron oxide precursor can be obtained; Step 2: The nickel-iron oxide precursor can be obtained; It is placed in the center of the tube furnace temperature zone for hot nitrogen treatment, using ammonia as the nitrogen source, inert gas argon as the protective gas, and setting the center temperature of the tube furnace to 400 °C for 2 h, to obtain primary nitrided Ni ₃ FeN/Ni ₃ N heterojunction catalyst; Step 3: The Ni ₃ FeN/Ni ₃ N heterojunction catalyst is soaked in the precursor solution again for several seconds, dried at room temperature, and the operation of step 2 is repeated to obtain the final NixFeN/ Ni3N (x = 1, ₃ ) heterojunction catalysts.

2. The method for preparing a bifunctional non-precious metal nitride catalyst applied to high-current electrolysis of urea for hydrogen production as claimed in claim 1, characterized in that, in the step 1 "first, an appropriate proportion of Fe(NO ₃ ) The amount of Fe(NO ₃ _{) 3} _· 9H ₂ O dissolved in ₅ mL of alcohol as a precursor solution” can be 0.4 g, 0.5 g and 0.75 g.

3. a kind of preparation method that is applied to the bifunctional non-precious metal nitride catalyst of high-current electrolytic urea hydrogen production as claimed in claim 1, is characterized in that, the cleaning treatment that step 1 nickel foam substrate passes through is: by foam substrate Soak in 3 M hydrochloric acid and ultrasonically wash for 10 minutes to remove possible oxides on the surface of the foam substrate; then ultrasonically wash with alcohol for 10 minutes to dissolve other impurities on the surface of the foamed nickel substrate; finally ultrasonically wash with deionized water 10 minutes to clean up.

4. a kind of preparation method that is applied to the bifunctional non-precious metal nitride catalyst of high current electrolysis of urea hydrogen production as claimed in claim 1, is characterized in that, in step 2, will be nitrogen source with ammonia gas, inert gas argon Gas as protective gas, characterized in that the flow of ammonia gas is 100 sccm, and the flow of argon gas is 10 sccm.

5. a kind of preparation method that is applied to the bifunctional non-precious metal nitride catalyst of high-current electrolytic urea hydrogen production as claimed in claim 1, is characterized in that, step 2 " is set to 400 ℃ of constant temperature 2 h”, the heating rate is required to be 3 °C/min.

6. a kind of preparation method that is applied to the bifunctional non-precious metal nitride catalyst of high current electrolysis urea hydrogen production as claimed in claim 1, is characterized in that, in step 3, will "Ni ₃ FeN/Ni in step 2 ₃ . The N-heterojunction catalyst is soaked in the precursor solution for a few seconds again.” It is characterized in that the proportion of the precursor solution is that 0.5 g Fe(NO ₃ ) _3.9H ₂ O is fully dissolved in 5 mL of alcohol solution, and the precursor solution is immersed in the The time in the body solution is 2-3s.